The present invention relates in general to the field of furniture constructed with synthetic woven material, and more particularly, to methods of stabilizing synthetic yarns of multiple filaments such as twisted yarns and woven synthetic yarn material using heat treatment during the manufacturing process.
Natural wicker has been used in the manufacture of furniture, baskets and other articles for many centuries. Natural wicker articles are manufactured from the twigs or branches of various plants that are first soaked in water in order to make them pliable, then woven to form into the article and finally allowed to dry. Furniture manufactured from wicker offers greater comfort than furniture manufactured from some other materials because of wicker's inherent compliancy. Further, wicker is light weight and reasonably strong, making it an important material in the manufacture of furniture.
The popularity of wicker furniture has increased significantly. The casual, informal appearance of wicker has made it especially popular for use in enclosed porches and other informal settings in homes, hotels and other establishments. Natural wicker, however, has had limited use in the outdoor furniture market, including patio furniture, pool furniture and the like. This is because natural wicker softens and weakens when wet, and is more susceptible to rotting and mildew than many other natural and man-made furniture materials.
Woven wicker typically comprises a warp yarn, i.e., a yarn running straight through the woven material and providing support, and a weft yarn, i.e., a yarn used as filler that is woven around the warp yarn. Numerous styles of weave are used in the manufacture of wicker furniture. The various styles of weave result in a different look, feel, strength and weight of the finished woven product. In a simple weave pattern, the warp yarns are spaced apart and arranged parallel to each other. The weft yarns are woven over and under alternating warp yarns. Adjacent weft yarns pass on opposite sides of a given warp yarn. Variations of this pattern, such as passing the weft yarn over two adjacent warp yarns, are known in the art.
Polymer yarns have also been used to manufacture wicker-like furniture. By way of example, a polymer yarn is known which is constructed as an elongated body, such as of indeterminate length, having a core surrounded by a polyvinylchloride (PVC) outer coating, for example, foamed PVC material which gives greater volume with less material. The outer coating may be formed of other synthetic materials such as polyamides, polyesters and the like. The yarn is typically made in a single step using a coextrusion process, as is known in the art. The inner core may include a single filament of polyester, or may include a plurality of polyester filaments bundled to form a single core. In addition, the core may be formed of other materials than polyester, monofilament or stranded, such as polyamides and the like. The core is designed to give the yarn greater mechanical strength over yarns formed only of polymer material.
The polymer yarn being constructed from foamed PVC material results in a lack of uniformity in the foaming of the PVC material during the extrusion process. This produces a yarn which lacks a uniform cylindrical appearance. Specifically, the outer surface of the yarn is deformed, such as by having undulations, mounds and/or depressed areas along the length of the yarn. The deformed shape of the outer surface of the yarn results in the yarn having a more natural look to that of real wicker. It is also known to provide the exterior surface of the polymer yarn with one or more random stripes of a contrasting color and/or one or more random grooves. The stripes and grooves can be continuous and/or intermittent along the exterior surface of the yarn. The yarn, however, can also have a more uniform cylindrical shape, as well as other shapes such as square, oval, triangular and the like. Polymer yarns as thus far described are known from U.S. Pat. Nos. 5,704,690; 5,845,970; and 6,179,382, as well as U.S. Des. Pat. Nos. 395,171; and 409,001, the disclosures of which are incorporated herein by reference.
As in the case of natural wicker, polymer yarns have been woven into a woven material which has been used in the manufacture of casual furniture suitable for the outdoor furniture market, including patio furniture, as well as for indoor use. Due to the nature of polymer yarns, it has been known to subject the woven material to a heat setting process prior to attaching the woven material to the frame forming the finished article of furniture. In this regard, a section of the woven material would be placed in an oven at an elevated temperature to cause the polymer material to soften whereby contiguous portions of the yarn would bond together stabilizing the shape of the woven material. The heat set woven material would be subsequently attached to the skeletal frame of an article of furniture to form, for example, a seat portion, a back rest portion or the like.
Heat setting the woven material renders the material less flexible, and therefore, more difficult to conform and attach to the skeletal frame of an article of furniture. In addition, certain components of the furniture article are only wrapped with a continuous strand of polymer yarn without forming a weave. As this wrapped portion is not subject to a heat setting process, it is possible that the wrapping will loosen during use of the furniture article.
It is therefore desirable to provide improvements in the manufacture of furniture articles including the use of polymer yarns and woven material therefrom, and more particularly, to a heat setting process which overcomes the disadvantages noted with respect to the aforementioned furniture articles.